Bonded structures

ABSTRACT

A bonded structure can include a first element having a first interface feature and a second element having a second interface feature. The first interface feature can be bonded to the second interface feature to define an interface structure. A conductive trace can be disposed in or on the second element. A bond pad can be provided at an upper surface of the first element and in electrical communication with the conductive trace. An integrated device can be coupled to or formed with the first element or the second element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/457,116, filed Feb. 9, 2017, titled “BONDED STRUCTURE,” and U.S. Provisional Patent Application No. 62/458,441, filed Feb. 13, 2017, titled “BONDED STRUCTURE,” the entire disclosures of which are hereby incorporated herein by reference.

BACKGROUND Field

The field generally relates to bonded structures, and in particular, to bonded structures having a reduced lateral footprint.

Description of the Related Art

In semiconductor device fabrication and packaging, some integrated devices are sealed from the outside environs in order to, e.g., reduce contamination or prevent damage to the integrated device. For example, some microelectromechanical systems (MEMS) devices include a cavity defined by a cap attached to a substrate with an adhesive such as solder. However, some adhesives may be permeable to gases, such that the gases can, over time, pass through the adhesive and into the cavity. Moisture or some gases, such as hydrogen or oxygen gas, can damage sensitive integrated devices. Other adhesives, such as solder, create their own long term reliability issues. Accordingly, there remains a continued need for improved seals for integrated devices.

Furthermore, regardless of whether the devices are sealed from the outside environs, or whether the device includes a cavity, in various types of bonded structures, bond pads for connecting to external devices, substrates, or other elements may occupy valuable space or area in the package or on the device. It can thus be desirable to provide a bonded structure in which the lateral footprint of the package or device is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic side sectional view of a bonded structure, according to various embodiments.

FIGS. 1B-K are partial schematic sectional plan views of various embodiments of an interface structure defined along a bonded interface of the bonded structure.

FIG. 2A is a schematic sectional plan view of an interface structure of the bonded structure shown in FIGS. 1A-1B.

FIG. 2B is a schematic sectional plan view of an interface structure having one or more electrical interconnects extending through the bonded interface.

FIG. 2C is a schematic sectional plan view of the interface structure of FIG. 1C.

FIG. 2D is a schematic sectional plan view of an interface structure having a plurality of conductive interface features disposed about a cavity to define an effectively annular profile, with each conductive interface feature comprising a mostly annular profile.

FIG. 2E is a schematic sectional plan view of an interface structure having a plurality of conductive interface features disposed about a cavity to define an effectively annular profile, wherein the plurality of conductive features comprises a plurality of segments spaced apart by gaps.

FIG. 2F is a schematic side sectional view of a bonded structure, according to some embodiments.

FIG. 2G is a schematic side sectional view of a bonded structure, according to various embodiments.

FIGS. 2H and 2I are schematic plan views of interface structures that comprise conductive interface features including an array of conductive dots or other discrete shapes, as viewed from the plan view.

FIG. 2J is a schematic side sectional view of a bonded structure having one or more bond pads positioned outside a bonded interface between first and second elements.

FIG. 2K is a top plan view of the bonded structure shown in FIG. 2J.

FIG. 2L is a schematic side sectional view of a bonded structure having one or more bond pads disposed on an upper surface of the bonded structure, according to various embodiments.

FIG. 2M is a top plan view of the bonded structure shown in FIG. 2L.

FIG. 2N is a chart that plots the percent increase in the number of bonded structures or dies per wafer versus die area for bonded structures in which bond pad ledges have been eliminated on one side, two sides, three sides, or four sides of the bonded structure or die.

FIG. 2O is a schematic side sectional view of a bonded structure, according to another embodiment.

FIG. 3 is a schematic side sectional view of a portion of a bonded structure that includes a crack stopper connected with the conductive interface features of the interface structure.

FIGS. 4A-4C are schematic plan views of bonded structures that increase tolerance for misalignments when corresponding interface features are bonded together.

FIGS. 5A-5D are schematic plan views of an interface structure that increases tolerance for misalignments when corresponding interface features on each semiconductor element are bonded together.

FIGS. 6A-6B are schematic plan views of an interface structure that increases tolerance for misalignments when corresponding interface features on each semiconductor element are bonded together, according to another embodiment.

FIG. 7A is a schematic plan view of a conductive interface feature in which a plurality of inner regions of non-conductive interface features are disposed within a crosswise grid structure defined by intersecting conductive interface features.

FIG. 7B is a schematic plan view of a bonded interface structure formed by bonding two interface features.

FIG. 7C is a schematic plan view of the bonded interface structure of FIG. 7B, with a plurality of electrical interconnects disposed within inner regions of the non-conductive interface feature.

FIG. 8 is a schematic diagram of an electronic system incorporating one or more bonded structures, according to various embodiments.

DETAILED DESCRIPTION

Various embodiments disclosed herein relate to interface structures that connect two elements (which may comprise semiconductor elements) in a manner that effectively seals integrated devices of the semiconductor elements from the outside environs. For example, in some embodiments, a bonded structure can comprise a plurality of semiconductor elements bonded to one another along an interface structure. An integrated device can be coupled to or formed with a semiconductor element. For example, in some embodiments, the bonded structure can comprise a microelectromechanical systems (MEMS) device in which a cap (a first semiconductor element) is bonded to a carrier (a second semiconductor element). A MEMS element (the integrated device) can be disposed in a cavity defined at least in part by the cap and the carrier.

In some arrangements, the interface structure can comprise one or more conductive interface features disposed about the integrated device, and one or more non-conductive interface features to connect the first and second semiconductor elements and to define an effectively annular or effectively closed profile. In some embodiments, the interface structure can comprise a first conductive interface feature, a second conductive interface feature, and a solid state non-conductive interface feature disposed between the first and second conductive interface features. In some embodiments, each semiconductor element can comprise an associated conductive interface feature, and the conductive interface features can be directly bonded to one another to connect the two semiconductor elements.

Various embodiments disclosed herein relate to stacked and bonded structures for reducing the overall lateral footprint of the device or package. The connective interface features can connect through the upper surface of the two semiconductor elements to electrically connect to bond pads on the upper surface of the upper element with metallic traces formed in one or more of the two elements. The bond pads can provide electrical interconnection for integrated devices within one or both of the semiconductor elements, including any devices (e.g., MEMS) exposed to any cavity defined between the elements, thus obviating separate bond pads outside the real estate of the upper element. The cavity can be formed within the upper element, within the upper element, or by the upper and lower elements. Accordingly, the lateral extent of the bonded structure can be reduced.

FIG. 1A is a schematic side sectional view of a bonded structure 1, according to various embodiments. FIG. 2A is a schematic sectional plan view of an interface structure 10 of the bonded structure 1 shown in FIGS. 1A-1B. The bonded structure 1 can include a first semiconductor element 3 bonded to a second semiconductor element 2 along the interface structure 10. As explained herein, corresponding bonding layers 11 of the first and second semiconductor elements 3, 2 can be directly bonded to one another without an intervening adhesive. As explained below, the interface structure 10 can include conductive interface features 12 embedded in a surrounding non-conductive interface feature 14. In various embodiments, a barrier or seed layer (not illustrated) can be provided on the non-conductive interface feature 14, e.g., lining a trench formed in the feature 14. The conductive interface feature 12 (which may comprise, e.g., copper) can be provided over the barrier layer, if present. The barrier layer can comprise any suitable material that can prevent migration of the material of the conductive interface feature 12 into the non-conductive feature 14. For example, in various embodiments, the barrier layer can comprise an insulating material, such as silicon nitride (SiN), or a conductive material, such as titanium (Ti), titanium nitride (TiN), titanium tungsten (TiW), tantalum (Ta), tantalum nitride (TaN), etc. Multiple lining layers can be provided to serve as barriers and/or to electrically isolate the conductive interface feature 12.

As explained herein, the bonding layers 11 of each element 3, 2 can include conductive and non-conductive interface features that can bond to define a seal. As shown in FIG. 1A, the interface features 12, 14 can extend vertically into the semiconductor elements (e.g., into and through the bonding layers 11), such that the interface features 12, 14 can extend in a direction from one semiconductor element towards the other semiconductor element, e.g., vertically relative to the bonded structure. In various embodiments, the interface features 12 can extend from the bond interface entirely into each semiconductor substrate of each semiconductor element on either side of the bond interface. The first and second semiconductor elements can define a cavity 5 in which an integrated device 4 is at least partially disposed. In the illustrated embodiment, the first semiconductor element 3 can comprise a cap that is shaped to define the cavity, or that is disposed over a cavity in the second semiconductor element 2. For example, the semiconductor element 3 can comprise a wall 6 disposed about the integrated device 4 and separating the cavity 5 from the outside environs. In various embodiments, the wall 6 and cap can comprise a semiconductor material, such as silicon. In other embodiments, the wall 6 and cap can comprise a polymer, ceramic, glass, or other suitable material. The cavity 5 can comprise an air cavity, or can be filled with a suitable filler material or gas. Although the first and second elements 2, 3 are described herein as semiconductor elements, in other embodiments, the first and second elements 2, 3 can comprise any other suitable type of element, which may or may not comprise a semiconductor material. For example, the elements 2, 3 can comprise various types of optical devices in some embodiments that may not comprise a semiconductor material. In other embodiments, optical devices may comprise a semiconductor material.

The second semiconductor element 2 can comprise a carrier having an exterior surface 9 to which the first semiconductor element 3 is bonded. In some embodiments, the carrier can comprise a substrate, such as a semiconductor substrate (e.g., a silicon interposer with conductive interconnects), a printed circuit board (PCB), a ceramic substrate, a glass substrate, or any other suitable carrier. In such embodiments, the carrier can transfer signals between the integrated device 4 and a larger packaging structure or electronic system (not shown). In some embodiments, the carrier can comprise an integrated device die, such as a processor die configured to process signals transduced by the integrated device 4. In the illustrated embodiment, the integrated device 4 comprises a MEMS element, such as a MEMS switch, an accelerometer, a gyroscope, etc. The integrated device 4 can be coupled to or formed with the first semiconductor element 3 or the second semiconductor element 2.

In some configurations, it can be important to isolate or separate the integrated device die 4 from the outside environs, e.g., from exposure to gases and/or contaminants. For example, for some integrated devices, exposure to moisture or gases (such as hydrogen or oxygen gas) can damage and/or change the performance of the integrated device 4 or other components. Accordingly, it can be important to provide an interface structure 10 that effectively or substantially seals (e.g., hermetically or near-hermetically seals) the cavity 5 and the integrated device 4 from gases. As shown in FIGS. 1A and 2A, the interface structure 10 can be arranged to prevent gases from passing through the interface structure 10 from an outer surface 8 of the structure 1 to an inner surface 7 of the structure 1.

The disclosed embodiments can utilize materials that have low gas permeation rates and can arrange the materials so as to reduce or eliminate the entry of gases into the cavity 5. For example, the permeation rate of some gases (such as hydrogen gas) through metals may be significantly less that the permeation rate of gases through other materials (such as dielectric materials or polymers). Hydrogen gas, for example, may dissociate into its component atoms at or near the outer surface 8. The dissociated atoms may diffuse through the wall 6 or interface structure 10 and recombine at or near the inner surface 7. The diffusion rate of hydrogen gas through metal can be approximately proportional to the square root of the pressure. Other gases, such as rare gases, may not permeate metals at all. By way of comparison, gases may pass through polymer or glass (silicon oxide) materials faster (e.g., proportional to the pressure) than metal materials since the gas molecules may pass through without dissociating into atoms at the outer wall 8, or the metal materials may have lower diffusivity to the gases.

Accordingly, the embodiments disclosed herein can beneficially employ metal that defines an effectively annular or closed pattern (see FIGS. 2A-2E) about the integrated device 4 to seal an interior region of the bonded structure (e.g., the cavity 5 and/or integrated device 4) from the outside environs and harmful gases. Beneficially, in some embodiments, the metal pattern can comprise a completely closed loop around the integrated device 4, which may improve sealing relative to other arrangements. In some embodiments, the metal pattern can comprise an incompletely annular pattern, e.g., mostly or partially annular, about the device 4, such that there may be one or more gaps in the metal. Since the permeation rate of gases through metals (such as copper) is less than the permeation rate of gases through dielectric or non-conductive materials (such as silicon oxide, silicon nitride, etc.), the interface structure 10 can provide an improved seal for an interior region of the bonded structure 1.

However, in some embodiments, it may be undesirable to utilize an interface structure 10 that includes only metal or a significant width of metal lines. If the interface structure 10 includes wide metal lines or patterns, then the metal may experience significant dishing during chemical mechanical polishing (CMP) or other processing steps. Dishing of the metal lines can adversely affect ability to bond the metal lines of first semiconductor element 3 to the second semiconductor element 2, particularly when employing direct hybrid metal-to-metal and dielectric-to-dielectric bonding techniques. Accordingly, in various embodiments, the interface structure 10 can include one or more conductive interface features 12 embedded with or otherwise adjacent to one or more non-conductive interface features 14. The conductive interface features can provide an effective barrier so as to prevent or reduce the permeation of gases into the cavity 5 and/or to the integrated device 4. Moreover, the conductive interface features can be made sufficiently thin and can be interspersed or embedded with the non-conductive interface features so as to reduce or eliminate the deleterious effects of dishing.

In some embodiments disclosed herein, the interface structure 10 can be defined by first interface features on the first semiconductor element and second interface features on the second semiconductor element. The first interface features (including conductive and non-conductive features) can be bonded to the corresponding second interface features to define the interface structure 10. In some embodiments, the interface structure 10 can comprise a separate structure that is separately bonded to the first semiconductor element 3 and the second semiconductor element 2. For example, in some embodiments, the wall 6 may be provided as a separate open frame with a generally planar semiconductor element 3 provided facing the frame. A second interface structure (not shown) can comprise an intervening structure that is directly bonded without an intervening adhesive between the open frame and semiconductor element 3 thereby forming a similar enclosed cavity 5 to that shown in FIG. 1A. The interface structure(s) 10 may provide mechanical and/or electrical connection between the first and second semiconductor elements 3, 2. In some embodiments, the interface structure 10 may provide only a mechanical connection between the elements 3, 2, which can act to seal the cavity 5 and/or the integrated device 4 from the outside environs. In other embodiments, the interface structure 10 may also provide an electrical connection between the elements 3, 2 for, e.g., grounding and/or for the transmission of electrical signals. As explained in more detail below in connection with FIGS. 4A-7C, the conductive interface features can be direct bonded to one another without an intervening adhesive and without application of pressure, heat, and/or a voltage. For example, bonding surfaces (e.g., bonding layers 11) of first and second interface features can be prepared. The bonding surfaces can be polished or planarized, activated, and terminated with a suitable species. For example, in various embodiments, the bonding surfaces can be polished to a root-mean-square (rms) surface roughness of less than 1 nm, e.g., less than 0.5 nm. The polished bonding surfaces can be activated by a slight etch or plasma termination. In various embodiments, the bonding surfaces can terminated with nitrogen or a nitrogen containing species, for example, by way of etching using a nitrogen-containing solution or by using a plasma etch with nitrogen. As explained herein, the bonding surfaces can be brought into contact to form a direct bond without application of pressure. In some embodiments, the semiconductor elements 3, 2 can be heated to strengthen the bond, for example, a bond between the conductive features. Additional details of direct bonding methods may be found at least in U.S. Pat. Nos. 9,385,024; 9,391,143; and 9,431,368, the entire contents of which are incorporated by reference herein in their entirety and for all purposes. In some embodiments, the conductive interface features 12 of both elements 3, 2 and the non-conductive interface features 14 of both elements 3, 2 are simultaneously directly bonded to one another. In other embodiments, the non-conductive interface features 14 can first be directly bonded to one another, then conductive interface features 12 can subsequently be directly bonded to one another after a thermal treatment that preferentially expands conductive interface features 12 that are dished or slightly recessed, for example less than 20 nm or 10 nm from adjacent non-conductive interface features 14.

It should be appreciated that, although the illustrated embodiment is directed to a MEMS bonded structure, any suitable type of integrated device or structure can be used in conjunction with the disclosed embodiments. For example, in some embodiments, the first and second semiconductor elements can comprise integrated device dies, e.g., processor dies and/or memory dies. In addition, although the disclosed embodiment includes the cavity 5, in other arrangements, there may not be a cavity. For example, the embodiments disclosed herein can be utilized with any suitable integrated device or integrated device die in which it may be desirable to seal active components from the outside environs and gases. Moreover, the disclosed embodiments can be used to accomplish other objectives. For example, in some arrangements, the disclosed interface structure 10 can be used to provide an electromagnetic shield to reduce or prevent unwanted electromagnetic radiation from entering the structure 1, and/or to prevent various types of signal leakage. Of course, the cavity may be filled with any suitable fluid, such as a liquid, gas, or other suitable substance which may improve, for example, the thermal, electrical or mechanical characteristics of the structure 1.

FIGS. 1B-1K are schematic, partial, sectional plan views of various embodiments of the interface structure 10. It will be understood that the illustrated patterns can extend completely annularly or incompletely annularly (e.g., mostly annularly), around the protected region, such as the cavity 5 of FIG. 1A, to define an effectively annular or effectively closed profile. As used herein, effectively annular structures may include round annular structures, as well as non-rounded annular structures that define an effectively closed profile (e.g., square or other polygon). As shown in FIGS. 1B-1K, the interface structure 10 can comprise one or a plurality of conductive interface features 12 and one or a plurality of non-conductive interface features 14. As shown in FIG. 1A, the conductive and non-conductive features 12, 14 can extend vertically through portions of the first and/or second semiconductor elements 3, 2, e.g., vertically through portions of the bonding layer(s) 11. For example, the conductive and non-conductive features 12, 14 can extend vertically through the first and/or second semiconductor elements 3, 2 (e.g., in a direction non-parallel or perpendicular to the major surface of the semiconductor elements 3, 2) by a vertical distance of at least 0.05 microns, at least 0.1 microns, at least 0.5 microns, or at least 1 micron. For example, the conductive and non-conductive features 12, 14 can extend vertically through the first and/or second semiconductor elements 3, 2 by a vertical distance in a range of 0.05 microns to 5 microns, in a range of 0.05 microns to 4 microns, in a range of 0.05 microns to 2 microns, or in a range of 0.1 microns to 5 microns. By extending the conductive and non-conductive features 12, 14 through portions of the first and/or second semiconductor elements 3, 2, the conductive and non-conductive features 12, 14 of the interface structure 10 can provide a seal without gaps between the semiconductor elements 3, 2. For example, in various arrangements, if conductive and non-conductive features 12, 14 are extended into the semiconductor substrate portion of elements 3, 2, a preferred seal comprised of only semiconductor and metal can be formed. The conductive and non-conductive features 12, 14 provided on semiconductor elements 3, 2 may provide generally planar surfaces for bonding the two semiconductor elements.

The conductive interface feature 12 can comprise any suitable conductor, such as a metal. For example, the conductive interface feature 12 can comprise copper, nickel, tungsten, aluminum, or any other suitable metal that is sufficiently impermeable to fluids/gases, such as air, hydrogen, nitrogen, water, moisture, etc. The non-conductive interface feature 14 can comprise any suitable non-conductive material, such as a dielectric or semiconductor material. For example, the non-conducive interface feature 14 can comprise silicon oxide or silicon carbide nitride in some embodiments. Beneficially, the use of both a conductive interface feature 12 and a non-conductive interface feature 14 can provide improved sealing to prevent gases from passing from the outside environs into the cavity 5 and/or to the device 4 and vice versa. As explained above, conductors such as metals may generally provide improved sealing for many gases. However, some non-conductive materials (e.g., dielectrics) may be less permeable to certain gases than conductors, metals, or semiconductors. Structurally mixing the conductive features 12 with the non-conductive features 14 may provide a robust seal to prevent many different types of gases and other fluids from entering the cavity and/or affecting the device 4.

In the embodiment of FIG. 1B, only one conductive interface feature 12, which may be completely annular, is provided. The conductive interface feature 12 can be embedded in one or more non-conductive interface features 14 to define an effectively annular or effectively closed profile. For example, in some embodiments, the conductive interface feature 12 can be embedded in a bulk non-conductive material. In other embodiments, layers of non-conductive material can be provided on opposing sides of the conductive interface feature 12. As shown in FIG. 2A, the conductive interface feature 12 can extend around the cavity 5 and/or the integrated device 4 in a completely annular pattern. In FIG. 2A, for example, the conductive interface feature 12 extends in a complete annulus, or closed shape, about the cavity 5 and/or device 4, such that the non-conductive material of the non-conductive feature 14 does not cross or intersect the conductive interface feature 12. In other embodiments, however (for example, see description of FIGS. 2D and 2E below), there may be one or more gaps between portions of the conductive interface feature 12, but without a direct path to the cavity 5. Individual elements of the conductive interface feature 12 can be incompletely annular in some embodiments. For example, individual elements of the conductive interface feature 12 can be mostly annular, e.g., extend about the cavity 5 and/or the integrated device 4 by at least 180°, at least 270°, at least 350°, or at least 355° (e.g.,) 360°, while cooperating to define an effectively annular or closed interface structure 10. Further, as explained above, the conductive interface feature 12 can extend vertically into and can be embedded in portions of the wall 6 and/or corresponding portions of the second semiconductor element 2.

The structure of FIG. 1A, including any of the example patterns of FIGS. 1B-1K, can be formed, for example, by semiconductor fabrication techniques, such as by forming metal lines on a substrate by deposition, patterning and etching and depositing oxide thereover, or by damascene processing. Desirably, the metal lines to be bonded are formed flush with surrounding non-conductive material, or slightly (e.g., 0.5 nm to 20 nm) recessed or protruding from the non-conductive material. Annular or mostly annular patterns of metal lines can be formed on both semiconductor elements 3, 2 using semiconductor processing, for directly bonding to one another and creating an effective metal seal against gas diffusion.

The interface structure 10 can have an interface width t₀ in a range of 1 micron to 1 mm, in a range of 0.1 microns to 100 microns, in a range of 0.1 microns to 50 microns, in a range of 1 micron to 25 microns, in a range of 0.1 microns to 10 microns, in a range of 0.1 microns to 1 micron, or in a range of 1 micron to 10 microns. The conductive interface feature 12 can have a conductor width t_(c) in a range of 0.1 microns to 50 microns. The non-conductive interface feature 14 can have non-conductor widths t_(i) in a range of 0.1 micron to 1 mm, in a range of 0.1 microns to 100 microns, in a range of 0.1 microns to 50 microns, in a range of 1 micron to 25 microns, in a range of 0.1 microns to 10 microns, in a range of 0.1 microns to 1 micron, or in a range of 1 micron to 10 microns. As explained above, the interface structure 10 disclosed in FIG. 1B can beneficially provide an effective seal against gases entering the cavity 5 and/or interacting with the device 4. Moreover, the interface structure 10 disclosed herein can be narrower in the horizontal dimension than other types of bonds or interfaces for a given bond strength, which can advantageously reduce the overall package footprint. In various embodiments, the interface structure 10 can be mostly or entirely defined by the non-conductive feature 14 (e.g., a dielectric), such that most or the entire bonded interface comprises a non-conductive material. As explained above, the width t_(i) of the insulator can be made very narrow (e.g., in a range of 1 microns to 100 microns, or in a range of 1 micron to 50 microns) while also providing a sufficiently strong bonding interface between the elements.

Turning to FIG. 1C, the interface structure 10 can include a plurality of conductive interface features 12 and an intervening solid state (e.g., non-gaseous) non-conductive interface feature 14 disposed between adjacent conductive interface features 12. FIG. 2C is a schematic plan view of the interface structure 10 shown in FIG. 1C. As with the implementation of FIG. 1B, the interface structure 12 can be disposed about the integrated device 4 and can comprise conductive features 12 arranged in an effectively annular or closed profile (e.g., a complete or incomplete annulus in various arrangements) to connect the first semiconductor element 3 and the second semiconductor element 2. In FIGS. 1C and 2C, the conductive features 12 comprise at least one complete or absolute annulus. In other embodiments, the conductive features can be shaped differently, but can be arranged to define an effectively annular or closed profile. The use of multiple conductive features 12 can provide multiple layers of highly impermeable material so as to reduce the inflow of gases into the cavity 5. Utilizing multiple thin conductive features 12 spaced by the non-conductive features 14, compared to wider features, can reduce the effects of dishing due to polishing for a given degree of overall impermeability. Thus, in various embodiments, multiple conductive features 12 can be arranged around one another, for example concentrically, mostly or completely about the device 4 and/or the cavity 5 to provide an effective gas seal.

Moving to FIG. 1D, in some embodiments, the conductive interface features 12 can comprise a plurality of annular conductors 12A disposed about the cavity 5 and/or device 4 in an effectively annular or closed pattern, and a plurality of crosswise conductors 12B connecting adjacent annular conductors 12A. Advantageously, the use of annular and crosswise conductors 12A, 12B can provide increased contact area for implementations that utilize direct bonding (explained below), and can provide an improved gas seal due to the beneficial permeation properties of the conductive material. As with the embodiments of FIGS. 1B-1C, in FIG. 1D, the conductive interface features 12 can delimit a closed loop such that the non-conductive features 14 do not intersect or cross the conductive features 12.

FIGS. 1E-1G illustrate conductive interface features 12 having a kinked, annular profile, in which a plurality of conductive segments 112 a-112 c are connected end-to-end and angled relative to adjacent segments. As with the embodiments of FIGS. 1B-1D, the features 12 can be disposed about the cavity 5 and/or device 4 in an effectively annular or closed pattern, e.g., in a complete annulus. The kinked profiles illustrated in FIGS. 1E-1G can comprise a first segment 112 a and a second segment 112 c spaced apart from one another in a transverse direction. The first and second segments 112 a, 112 c can be connected by an intervening transverse segment 112 b. The first and second segments 112 a, 112 c can be oriented along a direction generally parallel to the at least partially annular pathway around the cavity 5 and/or integrated device 4. The transverse segment 112 c can be oriented transverse or non-parallel to the first and second segments 112 a, 112 c. In some embodiments, the non-conductive interface features 14 may not cross the conductive features 12.

The kinked annular profile of the conductive interface features 12 can facilitate direct bonding with increased tolerance for misalignment, as compared with features 12 that are straight or non-kinked, while maintaining the benefits of narrow lines with respect to the effects of dishing after polishing. For example, the conductive interface features 12 may be sufficiently thin so as to reduce the effects of dishing but may traverse a pattern that facilitates alignment for bonding. The kinked profile can include any number of conductive interface features 12. For example, FIG. 1E illustrates a kinked profile with a single conductive interface feature 12. FIG. 1F illustrates a plurality of conductive interface features 12 spaced apart transversely by an intervening non-conductive interface feature 14. As with FIG. 1D, in FIG. 1G, spaced apart annular conductors 12A can be joined by crosswise conductors 12B. Skilled artisans would appreciate that other patterns may be suitable.

FIGS. 1H-1K illustrate conductive interface features 12 having an irregular or zigzag annular profile, in which a plurality of conductive segments 112 a-112 f are connected end-to-end and angled relative to adjacent segments by way of one or more bend regions 11. As shown in FIGS. 1H-1K, the segments 112 a-112 f may be arranged in an irregular pattern, in which the segments 112 a-112 f are angled at different orientations and/or have different lengths. In other arrangements, the segments 112 a-112 f may be arranged in a regular pattern at angles that are the same or periodic along the annular profile. In still other arrangements, each segment 112 a-112 f of the conductive features 12 can be curved or otherwise non-linear. These features may also increase tolerance for misalignment, relative to straight line segments, while still employing relatively narrow lines that are less susceptible to dishing and therefore easier to employ in direct metal-to-metal bonding.

FIG. 2B is a schematic sectional plan view of an interface structure 10 having one or more electrical interconnects extending through the interface structure 10. As with FIG. 2A, the conductive feature(s) 12 can be disposed within the interface structure 10 about the cavity 5 and/or integrated device 4 to define an effectively annular or closed profile, e.g., a completely annular profile. The conductive feature(s) 12 can comprise elongate feature(s) with a length greater than a width (e.g., with a length of at least five times the width, or at least ten times the width). Unlike the interface structure 10 shown in FIG. 2A, however, the interface structure 10 of FIG. 2B includes one or a plurality of electrical interconnects 20 extending vertically through one or more non-conductive interface features 14. The electrical interconnect(s) 20 can be in electrical communication with the integrated device 4 and/or other components of the bonded structure 1 so as to transfer signals between the various components of the structure 1. In some embodiments, the electrical interconnect(s) 20 can extend from the first semiconductor element 3 to the second semiconductor element 2. As shown in FIG. 2B, the electrical interconnect(s) 20 can be spaced inwardly and electrically separated from the conductive interface feature 12, which itself can also serve to electrically connect circuits in the first and second semiconductor elements 3, 2. In other embodiments, the electrical interconnect(s) 20 can be spaced outwardly from the conductive interface feature 12. In still other embodiments, as explained below, the electrical interconnect(s) 20 can extend through intervening non-conductive interface features 14 disposed between a plurality of conductive interface features 12.

The electrical interconnects 20 can provide electrical communication between the semiconductor elements 3, 2 through the interface structure 10. Providing the interconnects 20 in a direction non-parallel or transverse to the interface structure 10 can therefore enable the interface structure 10 to act as both a mechanical and electrical connection between the two semiconductor elements 3, 2. The interconnects 20 can comprise any suitable conductor, such as copper, aluminum, gold, etc. The interconnects 20 can comprise conductive traces or through-silicon vias in various arrangements. Moreover, as noted above, the interface features 12 may also serve as annular or mostly annular electrical interconnects, with or without the conventional interconnects 20.

FIG. 2D is a schematic sectional plan view of an interface structure 10 having a plurality of conductive interface features 12A, 12B disposed about a cavity 5 to define an effectively annular or closed profile, with each conductive interface feature 12A, 12B comprising an incompletely annular feature, e.g., a mostly annular feature extending more than 180°. For example, as shown in FIG. 2D, each conductive interface feature 12A, 12B can comprise a U-shaped structure, with the feature 12B disposed inwardly relative to the feature 12A by a non-conductive gap 39. Thus, in FIG. 2D, each conductive interface feature 12A, 12B may comprise a mostly annular profile, but with the gap 39 between the two interface features 12A, 12B such that any one of the interface features 12A, 12B does not necessarily define a closed loop. The structure 10 shown in FIG. 2D may still be effective at reducing the permeation of gases into cavity 5 and/or device 4, since the pattern of conductive interface features 12A, 12B combine to create an effectively annular or effectively closed structure about the cavity 5. Some gas may permeate through the gap 39, but the gas would have a very long path through the non-conductive material before it could reach the cavity 5 and/or contact the device 4, so as to overcome the higher diffusivity of gases in the non-conductive material 14 relative to the conductive material of the conductive interface features 12A, 12B. It should be appreciated that although two features 12A, 12B are shown herein, any suitable number of features 12 can be used.

FIG. 2E is a schematic sectional plan view of an interface structure 10 having a plurality of conductive interface features 12 disposed about a cavity 5 to define an effectively annular or closed profile, wherein the plurality of conductive features 12 comprises a plurality of segments spaced apart by non-conductive gaps 39. The segments that define each conductive interface feature 12 shown in FIG. 2E comprise linear segments, but in other embodiments, the segments can be curved. In FIG. 2E, some or all conductive interface features 12 on their own may not define a mostly annular pattern. Taken together, however, the pattern defined by the illustrated arrangement of conductive interface features 12 may define an effectively annular or closed pattern. Thus, even though a particular conductive interface feature 12 may not be annular, the arrangement of multiple conductive interface features 12 can define an effectively annular or closed pattern to seal an interior region of the bonded structure from gas entering the interior region from the outside environs, as shown in FIG. 2E.

The embodiments of FIGS. 2A-2E can accordingly comprise interface structures 10 that include conductive and non-conductive interface features 12, 14 that collectively define an effectively annular or closed diffusion barrier. For example, a particular conductive interface feature 12 can comprise a complete annulus or an incomplete annulus (e.g., mostly annular) that is arranged with other conductive and non-conductive interface features so as to define an effectively annular pattern or diffusion barrier. In some embodiments, the conductive interface feature can comprise other shapes, such as straight or curved segments, that are arranged about the cavity 5 and/or device 4 so as to define an effectively annular pattern or diffusion barrier. Moreover, the embodiments of FIGS. 2D and 2E can advantageously provide multiple conductive segments that can each serve as separate electrical connections, for example, for separate signal line connections, ground line connections and power line connections. Together those segments can provide effectively annular conductive patterns to serve as diffusion barriers. The effectively annular patterns described herein can beneficially provide a longer distance over which gases travel to reach the sensitive components of the structure 1, which can reduce the permeability of the structure 1.

FIG. 2F is a schematic side sectional view of a bonded structure 1, according to some embodiments. FIG. 2F is similar to FIG. 1A, except in FIG. 2F, the first semiconductor element 3 can comprise one or a plurality of electronic components 38 formed or coupled with various portions of the semiconductor element 3. For example, as illustrated, the semiconductor element 3 can comprise a plurality of electronic components 38A-38C. The electronic components 38A-38C can comprise any suitable type of electronic component. The electronic components 38 can comprise any suitable type of device, such as integrated circuitry (e.g., one or more transistors) or the like. In some embodiments, the electronic components 38 can communicate with the device 4, the second semiconductor element 2, and/or other components by way of the interconnects (see FIG. 2B) and/or by the conductive interface features 12. For example, the electronic components 38 can communicate with the second semiconductor element 2 by way of one or more conductive traces 36 that pass through the semiconductor element 3. The electronic components 38 and the traces 36 can be defined by semiconductor processing techniques, such as deposition, lithography, etching, etc. and can be integrated with the semiconductor element 3. The traces, for example, may be formed by conventional back-end-of-line interconnect metallization through multiple metal levels. Moreover, as shown in FIG. 2F, any of the embodiments disclosed herein can include one or a plurality of electronic components 37 formed (e.g., with semiconductor processing techniques) or coupled with the second semiconductor element 2. The electronic components 37 can comprise any suitable type of device, such as integrated circuitry or the like, and can communicate with the device 4, the first semiconductor element 3, and/or other components. For example, in some embodiments, one or more electronic components 37A can be defined within the semiconductor element 2 (e.g., buried within the semiconductor element 2 or exposed at the surface 9). In some embodiments, one or more electronic components 37B can be defined at or on the surface 9 of the semiconductor element 2.

FIG. 2G is a schematic side sectional view of a bonded structure 1, according to various embodiments. FIG. 2G is similar to FIGS. 1A and 2F, except in FIG. 2G, there may not be a cavity defined between the first and second semiconductor elements 3, 2. Rather, in the embodiment of FIG. 2G, the first and semiconductor elements 3, 2 may be bonded to one another without an intervening cavity. In the illustrated embodiment, as with the embodiments described herein, the semiconductor elements 3, 2 can be bonded to one another by way of an interface structure 10 that defines an effectively annular pattern or profile about the interior of the elements 3, 2. As explained herein, the semiconductor elements 3, 2 can be directly bonded to one another along at least the interface structure 10 to define the effectively annular profile, with conductive and nonconductive interface features defined therein. The effectively annular profile of the interface structure 10 can comprise any of the patterns disclosed herein. Even though there may be no cavity in the bonded structure 1 of FIG. 2G, the interface structure 10 may define an effective seal so as to protect sensitive electronic circuits or components 37 in the interior of the structure 1 from the outside environs, including, e.g., gases. It should be appreciated that any of the embodiments disclosed herein may be used in conjunction with bonded structures that do not include a cavity.

Moreover, as illustrated in FIG. 2G, the first semiconductor element 3 can comprise one or more electronic components 38 formed at or near the surface of the element 3, and/or within the body of the element 3. The second semiconductor element 3 can also include one or more electronic components 37 formed at or near the surface of the element 2, and/or within the body of the second semiconductor element 3. The electronic components 37, 38 can comprise any suitable type of element, such as electronic circuitry that includes transistors, etc. The components 37, 38 can be disposed throughout the elements 3, 2 in any suitable arrangement. In the embodiment of FIG. 2G, the first and second elements 3, 2 can comprise any combination of device dies, such as any combination of processor dies, memory dies, sensor dies, etc. In the illustrated embodiment, the interface structure 10 can be disposed about the periphery of the bonded structure 1 so as to seal the interior of the bonded structure 1 from the outside environs. In various embodiments, therefore, the interior of the bonded structure 1, e.g., the region within the effectively annular pattern defined by the interface structure 10, may or may not be directly bonded. In the illustrated embodiment, some components 37, 38 may be disposed within an interior region of the bonded structure 1, e.g., within the effectively closed profile defined by the interface structure 10. A first interconnect of the first semiconductor element 3 and a second interconnect of the second semiconductor element 2 can be directly bonded to one another within the interior region of the bonded structure 1 to connect components 37, 38 in the respective elements 3, 2. In addition, additional components may be disposed outside the interior region defined by the interface structure 10. Such additional components (such as integrated device dies) may also be directly bonded to one another outside the interior region.

FIGS. 2H and 2I are schematic plan views of interface structures 10 that comprise conductive interface features 12 including an array of conductive dots, as seen from the plan view. In FIG. 2H, the conductive interface features 12 comprise a ring of closely spaced dots about the cavity 5 (or the interior of the bonded structure generally). In FIG. 2I, the conductive interface features 12 comprise multiple rings of closely spaced dots, with an outer ring of features laterally offset relative to the inner ring of features so as to improve the sealability of the interface structure 10. Although two rings of features 12 are shown in FIG. 2I, it should be appreciated that the conductive features 12 can comprise a mesh of dots or discrete shapes spaced from one another so as to define the effectively annular pattern. The conductive interface features 12 and the nonconductive interface feature 14 can cooperate to define an effectively annular or effectively closed pattern that connects two semiconductor elements. It should be appreciated that, although the dots shown in FIGS. 2H-2I are illustrated as rounded (e.g., circular or elliptical), in other embodiments, the dots can comprise any suitable discrete shapes such as polygons. Moreover, as explained herein, in some embodiments, the conductive interface features 12 (e.g., the dots) may only act as bonding mechanisms between the two semiconductor elements 3, 2. In other embodiments, however, some or all conductive interface features 12 may act as electrical interconnects (such as the ends of the interconnects 20 or pads connected thereto) to provide electrical communication between the semiconductor elements 3, 2. It should be appreciated that the features of FIGS. 2H and 2I can be combined with the various other embodiments disclosed herein.

FIG. 2J is a schematic side sectional view of a bonded structure 1 having one or more bond pads 65 positioned outside a bonded interface between first and second elements 3, 2 (which may comprise semiconductor elements in some embodiments). FIG. 2K is a top plan view of the bonded structure 1 shown in FIG. 2J. Unless otherwise noted, components shown in FIGS. 2J-2K may be the same as or generally similar to like numbered components in FIGS. 1A-2I. For example, the bonded structure can include first and second elements 3, 2 directly bonded to one another along an interface structure 10 without an intervening adhesive. In other embodiments, the first and second elements 3, 2 may be bonded in other ways, such as by way of one or more adhesives. In various embodiments, the bonding layers 11 of each element 3, 2 can include conductive interface features that can bond directly to one another along the interface structure 10. In some embodiments, the conductive interface features can define a closed shape to seal the interface against diffusion as described elsewhere herein. In some embodiments, the bonding layers 11 of each element 3, 2 can include conductive and non-conductive interface features (not shown) that can bond to define a seal and an effectively closed or effectively annular profile. The first and second elements 3, 2 can define a cavity 5 in which an integrated device is at least partially disposed. In other embodiments, such as that shown in FIG. 2G, there may be no cavity between the two elements 3, 2. In other embodiments, any type of hybrid bond with isolated or embedded conductive portions can be used.

As shown in FIGS. 2J and 2K, the bond pads 65 can be disposed outside the effectively closed profile defined by the interface structure 10. For example, the bond pads 65 can be disposed on an outer ledge portion 67 of the second element 2. The bond pads 65 can be directly connected to the circuitry in the second element 2. The bond pads 65 can also be connected to circuitry in the first element 3 by way of conductive traces (not shown) defined in the first and/or second elements 3, 2. The bond pads 65 can be configured to electrically communicate with an external component, such as a package or system board, e.g. by wire bonds, solder balls, or other electrical connectors. The effectively closed profile can be defined by element 3, by element 2, or by both elements 2, 3.

As illustrated in FIG. 2K, the ledge portion 67 can have a ledge width dx along the side of the bonded structure 1 outside the bonded interface structure 10. The ledge width dx may undesirably increase the overall footprint of the structure 1. In various arrangements, the ledge width dx can be in a range of 50 microns to 250 microns, or in a range of 100 microns to 200 microns. Any suitable number of ledge portions may be provided about the periphery of the bonded interface structure 10. In FIG. 2K, for example the ledge portion 67 is provided along two perpendicular or non-parallel sides of the interface structure 10, but in other embodiments, two ledge portions 67 may be provided along two parallel sides of the interface structure 10, only one ledge portion 67 may be provided along only one side of the interface structure 10, or more than two ledge portions 67 (e.g., three or four) can be provided along more than two sides of the interface structure 10 (e.g., three or four sides). Other side numbers are possible with non-rectangular elements.

FIG. 2L is a schematic side sectional view of a bonded structure 1 having one or more bond pads 65 disposed at an upper surface 68 of the bonded structure 1, according to various embodiments. FIG. 2M is a top plan view of the bonded structure 1 shown in FIG. 2L. As shown in FIG. 2L, the one or more bond pads 65 can be provided at an exterior or upper surface 68 of the bonded structure 1, e.g. on the upper surface of the first element 3. While illustrated as sitting atop the upper surface 68, the skilled artisan will appreciate that the bond pads 65 may be recessed relative to a top surface of the bonded structure or buried beneath a passivation layer and exposed by openings therethrough. As explained above one or more conductive traces 36 can provide electrical communication between various components of the structure 1. In the illustrated embodiment, the traces 36 can connect with the bond pads 65 by way of a conductive interconnect 66 extending from a conductive trace 36 of the second element 2, through the interface structure 10 (e.g. by way of conductive interface features within the interface structure 10, which may be embedded in non-conductive interface features) and the body of the first element 3, to electrically connect to the bond pads 65. The interconnects 66 may also extend through at least a portion of the second element 2 to connect with traces 36 disposed in the body of the second element 2 (e.g., disposed in the bonding layer 11 of the element 2). In other embodiments, the interconnects 66 may not penetrate the second element 2, e.g., in embodiments in which the traces 36 or other conductors are disposed at the top surface of the second element 2 (e.g., on the top surface of the bonding layer 11 of the element 2). The conductive traces 36 and interconnects 66 can be separately provided for each of one or more bond pads 65. In some embodiments, one or more of the bond pads 65 may connect to integrated devices or circuitry within the first element 3, and thus not be directly associated with interconnects 66 or traces 36 that communicate through the interface. Of course, the traces 36 and interconnects 66 that communicate with multiple bond pads 65 at the upper surface 68 should be insulated from any sealing ring (not shown) formed by direct conductor bonding at the interface between the first and second elements 3, 2. Although the bonded structure 1 of FIG. 2L includes a cavity 5, in other embodiments, no cavity may be provided. In various embodiments, for example, an integrated device can be disposed at or near the surface of the element 3 (or the element 2), and/or within the body of the element 3 (or the element 2).

Beneficially, providing the interconnect 66 through the interface structure 10 can reduce the overall footprint of the bonded structure 1 as compared with the arrangement shown in FIGS. 2J and 2K. For example, by routing the interconnect 66 through the interface structure 10, the ledge region of FIGS. 2J and 2K can be eliminated, reducing the lateral footprint by dx for each ledge region eliminated. In various embodiments, the embodiment of FIGS. 2L and 2M can increase the number of bonded structures per wafer in a range of 3% to 125%. For example, for structures 1 with one bond pad ledge region 67, the embodiment of FIGS. 2L-2M can increase the number of bonded structures per wafer by an amount in a range of 3% to 30%. For structures 1 with two bond pad ledge regions 67, the embodiment of FIGS. 2L-2M can increase the number of bonded structures per wafer by an amount in a range of 7% to 60%. For structures 1 with three bond pad ledge regions 67, the embodiment of FIGS. 2L-2M can increase the number of bonded structures per wafer by an amount in a range of 10% to 90%. For structures 1 with four bond pad ledge regions 67, the embodiment of FIGS. 2L-2M can increase the number of bonded structures per wafer by an amount in a range of 16% to 125%.

In various embodiments disclosed herein, the bonded structure 1 with bond pads 65 on an upper surface of the bonded structure 1 can beneficially increase the number of dies per wafer (dpw) (e.g., bonded structures per wafer) with the elimination of ledges or ledge regions from one, two, three, and/or four sides of the die or bonded structure. Furthermore, FIG. 2N is a chart that plots the percent increase in the number of bonded structures or dies per wafer versus die area for bonded structures in which bond pad ledges have been eliminated on one side, two sides, three sides, or four sides of the bonded structure or die. As shown in FIG. 2N, for example, the percent increase in the number of bonded structures or dies per wafer is higher for bonded structures or dies in which the ledges have been eliminated from four sides as compared to only one side.

FIG. 2O is a schematic side sectional view of a bonded structure 1, according to another embodiment. Unless otherwise noted, components shown in FIG. 2O may be the same as or generally similar to like-numbered components shown in FIGS. 2L and 2M. In FIG. 2L, the first and second elements 3, 2 are illustrated as being generally laterally coextensive, e.g., the overall widths of the elements 3, 2 as shown in FIG. 2L are approximately the same. Unlike in FIG. 2L, however, in FIG. 2O, one of the elements (e.g., the lower or second element 2) may be larger than the first element 3. For example, as shown in FIG. 2O, the second element can have a shelf portion 69 that extends laterally beyond outer edges of the first element 3. Nevertheless, the overall footprint of the bonded structure 1 may be relatively small as compared with the structure 1 shown in FIGS. 2J-2K. For example, the shelf portion 69 may only slightly extend past the outer edges of the first element 3 by a distance d, as shown in FIG. 2O. The distance d may be sufficiently small such that wire bonding the first and second elements 3, 2 to pads on the shelf portion 69 may be difficult or impossible. In some embodiments, the lateral area or footprint of the second element 2 may be the same as the lateral area or footprint of the first element 3 (see FIG. 2L). In FIG. 2O, the lateral area or footprint of the second element 2 can be in a range of 100% to 125%, in a range of 100% to 110%, or in a range of 100% to 105% of the area or lateral footprint of the first element 3. In various embodiments, no bond pads may be provided on the shelf portion 69. Indeed, to the extent there is a shelf portion 69, it may be very narrow and insufficiently wide to allow for wire bonding. In other embodiments, the shelf portion 69 may include bond pads in addition to those on the upper surface of the upper element 3. In various embodiments, an entirety of the shelf portion 69 can be covered by the bonding layer 11. In some embodiments, an additional layer, e.g., a passivation layer can also be provided over the bonding layer and can extend across the element 2, including over the shelf portion 69. While not shown, the passivation layer may be pierced by conductors connected to the trace 36 within the footprint of the first element 3, but is not pierced by conductors in the exposed shelf portion 69. Although the trace 36 in FIGS. 2J, 2L, and 2O is shown as being disposed within the bonding layer 11, it should be appreciated that the trace(s) 36 can be disposed in the main body of the element 2 (e.g. the bulk silicon or semiconductor material for semiconductor elements).

The interconnect 66 can be formed in any suitable manner. In some embodiments, the interconnect 66 can be formed prior to bonding the first and second elements 3, 2. In other embodiments, the interconnect 66 can be formed after bonding the first and second elements 3, 2. In some embodiments, for example, the interconnect 66 can be formed in a via-first process, in which the interconnect 66 can be initially buried within the first element 3 and exposed through a subsequent removal or thinning process (such as etching, grinding, etc.). In other embodiments, the interconnect can be formed in a via-last process, in which a trench is defined (e.g., etched) in the first element 3, and an insulating liner and the metallic interconnect 66 are deposited in the trench. Although the interconnect 66 is illustrated as extending through the thickness of the first element 3 in FIG. 2L, in other arrangements, the interconnect 66 may also, or alternatively, extend through the second element 2. Moreover, as explained above, in some embodiments, the interconnect 66 can communicate with the second element 2 by way of conductive interface features disposed along the interface structure 10. In some embodiments, the interconnect 66 can extend through, and/or can be defined within, the interface structure 10, such that the interconnect 66 can form at least part of the conductive interface feature(s) of the interface structure 10. For example, in some embodiments, the interconnect 66 can be exposed on a lower surface of the first element 3 prior to bonding, and can directly bond to a corresponding conductive feature (which may itself comprise another interconnect) of the second element 2. As with the conductive features described above, in various embodiments, barrier, seed and/or insulating layer(s) can line trench(es) and/or via(s) of the dielectric, and the interconnect 36 can be provided over any such liners.

FIG. 3 is a schematic side sectional view of a portion of a bonded structure 1 that includes a crack stopper 13 connected with the conductive interface features 12 of the interface structure 10. The crack stopper 13 includes alternating wider and narrower segments as it vertically connects through back-end-of-line interconnect structures within the die, and accordingly can prevent or reduce the propagation of cracks in one of the semiconductor elements (e.g., the second element 2). By introducing low K dielectrics into the back-end of the line (BEOL) interconnect layer of a functional device die, the fracture resistance of the dielectric may be substantially reduced and may be comparable or significantly lower than that of silicon. Therefore, preventing cracking and delamination of the low K dielectric layers at the edge of a die may be challenging under the stresses that arise from chip package interactions. Beneficially, cracking at the edge of the chip can be reduced by incorporating the patterned metal interface structures (e.g., the crack stopper 13) around the perimeter in the low K dielectrics that act as a crackstop by increasing the fracture resistance near the edge of the chip.

FIGS. 4A-4C are schematic plan views of bonded structures 10 that increase tolerance for misalignments when corresponding interface features from each of the semiconductor elements 3, 2 are bonded together. In some embodiments, the bonded structures 10 of FIGS. 4A-4C can be arranged to provide an effective gas seal when corresponding conductive interface features 12, 12′ from adjacent semiconductor elements are misaligned. As explained herein, in various embodiments, the interface structure 10 can be defined by first interface features disposed on the first semiconductor element 3 and second interface features disposed on the second semiconductor element 2. For example, as shown in FIGS. 4A-4C, a first conductive interface feature 12 and a first non-conductive interface feature 14 can be disposed on the first semiconductor element 3. A second conductive interface feature 12′ and a second non-conductive interface feature 14′ can be disposed on the second semiconductor element 2. The first and second interface features can comprise the materials described above in connection with FIGS. 1A-2B. For example, in various embodiments, the first and second conductive interface features 12, 12′ can comprise copper. In various embodiments, the first and second non-conductive interface features 14, 14′ can comprise silicon oxide.

As with the bonded structures 1 of FIGS. 1A-2B, in some embodiments, the interface structure 10 of FIGS. 4A-4C can extend around the cavity 5 and/or integrated device 4 to define an effectively annular pattern, e.g., the conductive features can delimit a complete annulus or an incomplete annulus that define an effectively annular pattern. Disposing the interface structure 10 in an effectively annular pattern can advantageously seal the cavity 5 and/or integrated device 4 from gases entering the bonded structure 1. In other embodiments, however, the interface structure 10 of FIGS. 4A-4C can be used as an interface for applications other than, or in addition to, gas sealing. For example, the interface structure 10 of FIGS. 4A-4C can be used in any application to account for misalignment when conductive features are bonded to one another. In some embodiments, the interface structure 10 of FIGS. 4A-4C can provide one or more direct electrical and/or mechanical connections between the semiconductor elements. In various embodiments, the interface structure 10 of FIGS. 4A-4C may or may not be disposed about the integrated device 4 in an annular pattern. In some embodiments, for example, the interface structure 10 may be disposed at a plurality of discrete locations on the corresponding external surfaces of the semiconductor elements, such as for the interconnects 20 described below with respect to FIG. 7C. In such embodiments, the interface structure 10 can act as an electrical interconnection between the semiconductor elements. The first and second interface features can be bonded to one another in a variety of ways. In some embodiments, the first and second interface features can be directly bonded to one another without an intervening adhesive and without the application of pressure and/or temperature.

In embodiments that utilize direct bonding for the interface structure 10, bonding surfaces of the first and second interface features can be prepared. For example, a bonding surface of the first conductive interface feature 12 and the first non-conductive interface feature 14 can be directly bonded to a corresponding bonding surface of the second conductive interface feature 12′ and the second non-conductive interface feature 14′, without an intervening adhesive and without the application of pressure or a voltage. The bonding surfaces can be polished or planarized, activated, and terminated with a suitable species. The bonding surfaces can be brought into contact to form a direct bond without application of pressure. In some embodiments, the semiconductor elements 3, 2 can be heated to strengthen the bond, for example, a bond between the conductive features. Additional details of the direct bonding processes used in conjunction with each of the disclosed embodiments may be found throughout U.S. Pat. Nos. 7,126,212; 8,153,505; 7,622,324; 7,602,070; 8,163,373; 8,389,378; and 8,735,219, and throughout U.S. patent application Ser. Nos. 14/835,379; 62/278,354; 62/303,930; and Ser. No. 15/137,930, the contents of each of which are hereby incorporated by reference herein in their entirety and for all purposes.

In the structure 10 of FIG. 4A, the conductive interface features 12, 12′ are relatively thin, such that dishing from polishing can be avoided and direct metal-to-metal bonding facilitated. If the respective interface features are laterally misaligned, however, a conductive bond 35 between the features 12, 12′ is relatively small. The conductive bonds 35 shown in FIG. 4A may comprise isolated regions of contact, which may provide an inadequate gas seal (and/or an inadequate electrical connection).

Accordingly, as shown in FIGS. 4B-4C, the conductive interface features 12, 12′ can be made sufficiently wide so as to ensure adequate conductivity of electrical connections and also provide a better diffusion barrer. The thick conductive features 12, 12′ of FIGS. 4B-4C can advantageously enable larger conductive bonds 35, and also improve the gas sealing capabilities (and/or electrical connections) of the interface structure 10. In FIG. 4B, for example, the thickness of the conductive features 12, 12′ can be made to be thicker than a maximum misalignment tolerance of the bonding procedure. Thus, if a bonding procedure has a misalignment tolerance of T, then the lateral thickness of the conductive interface features 12, 12′ can be greater than or equal to T. In various direct bonding procedures, for example, the misalignment tolerance T can be in a range of 0.1 microns to 25 microns. Dimensioning the thickness of the conductive feature 12, 12′ to equal or exceed the maximum misalignment tolerance T of the bonding process can ensure that the conductive bond 35 forms a closed structure.

In the embodiment of FIG. 4C, the thickness of the conductive interface features 12, 12′ can be selected to be larger than the space provided for the intervening non-conductive interface features 14, 14′. Thus, in FIG. 4C, the conductive features 12 can be thicker than the non-conductive features 14, 14′. Dimensioning the conductive features 12 in such a manner can ensure that the conductive features 12, 12′ mate along a continuous interface. Accordingly, the relatively thick conductive features 12, 12′ of FIGS. 4B-4C can provide effective connection between conductive interface features 12, 12′ during bonding even in the presence of misalignment, and a continuous interface can provide an annular or mostly annular barrier to diffusion.

FIGS. 5A-5D are schematic plan views of an interface structure 10 that increase tolerance for misalignments when corresponding interface features 10A, 10B on each semiconductor element 3, 2 are bonded together, while providing an effective metal diffusion barrier. As explained above in connection with FIGS. 4A-4C, it can be important to account for misalignments when bonding (e.g., direct bonding) two corresponding interface features 10A, 10B. The interface features 10A, 10B can be disposed on exterior surfaces of the first and second semiconductor elements 3, 2, respectively. The interface features 10A, 10B can comprise one or more conductive interface features 12, 12′, which can also be embedded in or coupled with one or more non-conductive interface features 14, 14′. The conductive interface features 12, 12′ can be brought together and directly bonded without an intervening adhesive in some embodiments. In some embodiments, the non-conductive interface features 14, 14′ can also be directly bonded to one another. In other embodiments, an adhesive can be used to bond the elements. The conductive features 12, 12′ can define a conductive bond 35 along regions where the features 12, 12′ overlap with one another.

To increase tolerance for misalignments, the conductive interface features 12, 12′ can comprise a plurality of wide sections 16 alternately arranged and connected with a plurality of narrow sections 15. For example, as shown in FIG. 5A, each wide section 16 can be connected between two narrow sections 15, and each narrow section 15 can be connected between two wide sections 16. The narrow section 15 can have a first width t in a range of 0.1 microns to 25 microns. The wide section can have a second width w less than t and in a range of 0.5 microns to 50 microns. Moreover, as shown in FIG. 5A, the wide sections 16 can be spaced from one another by a first distance g in which the intervening non-conductive interface feature 14 can be disposed. the wide and narrow sections 16, 15 can be connected end-to-end, the narrow sections 15 can have a length that is the same as the first distance g. The first distance g can be in a range of 0.1 microns to 50 microns. The thin sections can be spaced from one another by a second distance h, which may also comprise a length of the wide sections 16. The second distance h can be in a range of 0.2 microns to 50 microns. Moreover, an outermost edge of the wide sections 16 can be offset relative to an outermost edge of the narrow sections 15 by a lateral offset x, which as explained below can correspond to the bonding procedure's maximum alignment tolerance in the x direction. The lateral offset x can be in a range of 0.1 microns to 25 microns.

Advantageously, the wide segments 16 can be provided to improve the gas sealing capabilities of the bonded structure 1, as explained above. The narrow segments 14 can be provided to reduce the effects of dishing that may occur due to polishing, thereby facilitating direct conductor to conductor bonding. FIG. 5B illustrates the interface structure 10 after bonding in which there is little to no misalignment of the respective interface features 10A, 10B. As shown in FIG. 5B, the conductive features 12, 12′ completely overlap one another at a half-pitch offset in the y-direction as shown in FIG. 5A such that the bonded conductive regions provide closed pathways at a large conductive bond 35. As shown in FIG. 5B, in the case where there is little to no misalignment, the conductive features 12, 12′ completely overlap laterally at the conductive bond 35, i.e., parallel to the lateral offset x, because the lateral offset of the outermost edge of the wide sections 16 can be selected to correspond to the bonding procedures' maximum alignment tolerance. For example, for a lateral misalignment tolerance x for a particular bonding procedure, the first and second widths t, w can be selected to satisfy the relationship x≤(w−t)/2. For a longitudinal misalignment tolerance y during bonding, for a particular bonding procedure, the first and second distances g, h can be selected to satisfy the relationship y≤(h−g)/2. Satisfying these relationships ensure that a continuous overlap, or bond line, between the conductive features 12, 12′ of the different semiconductor elements 3, 2.

FIG. 5C illustrates the bonded interface structure 10 when the interface feature 10A, 10B are misaligned laterally by the misalignment tolerance x and longitudinally by the misalignment tolerance y. As shown in FIG. 5C, even when the interface features 10A, 10B are misaligned by x and y for a particular bonding procedure, the resulting bonded interface structure 10 comprises significant and continuous overlap between the conductive interface features 12, 12′ at the conductive bond 35, which can provide an effectively annular diffusion barrier, e.g., a completely annular or mostly annular barrier to diffusion.

FIG. 5D illustrates the bonded interface structure 10 when the interface features 10A, 10B are misaligned laterally by the misalignment tolerance x plus the first width t, with longitudinal misalignment less than (h−g)/2. As shown in FIG. 5D, when there is longitudinal misalignment less than (h−g)/2 (e.g., parallel to y), the bonded interface structure 10 of FIG. 5D can accommodate lateral misalignments that are even larger than the misalignment tolerance x of the bonding procedure, because the additional width of the narrow sections 15 can contribute additional bonding regions at the conductive bond 35 when there is longitudinal misalignment less than (h−g)/2. While the overlapping bond region is laterally less wide than in FIG. 5C, the metal to metal bond interface remains continuous and provides a better diffusion barrier than, for example, oxide.

FIGS. 6A-6B are schematic plan views of an interface structure 10 that increases tolerance for misalignments when corresponding interface features 10A, 10B on each semiconductor element 3, 2 are bonded together, according to another embodiment. In the embodiment of FIGS. 6A-6B, the non-conductive interface features 14, 14′ can comprise a plurality of inner regions 114 a and a plurality of outer regions 114 b. The inner regions 114 a can be completely surrounded (in a horizontal plane) by the conductive interface features 12, 12′. In the illustrated embodiment, the plurality of the conductive interface features 12, 12′ can comprise a number of blocks 17 that are disposed around (e.g., completely around) the inner regions 114 a of the non-conductive interface regions 14, 14′. The outer regions 114 b of the non-conductive interface regions 14, 14′ can be disposed in gaps between adjacent outer blocks 17.

In some embodiments, a first width t₁ of the blocks 17 can be greater than a second width t₂ of the inner regions 114 a and/or the outer regions 114 b. For example, in some embodiments, the first width t₁ of the blocks 17 can be in a range of 0.2 microns to 25 microns. The second width t₂ of the inner regions 114 a and/or the outer regions 114 b can be in a range of 0.1 microns to 20 microns. Dimensioning the blocks 17 to be larger than the regions 114 a, 114 b can enable the conductive features 12, 12′ to have significant overlapping conductive bond 35, as shown in the bonded interface structure 10 of FIG. 6B.

FIG. 7A is a schematic plan view of a conductive interface feature 10A in which a plurality of inner regions 114 a of non-conductive interface features 14 are disposed within (surrounded by) a lattice. For example, the interface feature 10A shown in FIG. 7A comprises a crosswise grid structure defined by intersecting conductive interface features 12. FIG. 7B is a schematic plan view of a bonded interface structure 10 formed by bonding two interface features 10A, 10B. As shown in FIG. 7A, the conductive feature 12 can include a plurality of wide blocks 18 interconnected by narrow conductive segments 19. The wide blocks 18 can provide improved gas sealing capabilities, and the narrow conductive segments 19 can be provided to avoid the negative effects of dishing due to polishing procedures, thereby facilitating direct metal to metal bonds. In FIG. 7A, the blocks 18 and segments 19 are arranged in a grid in which the conductive features 12 are disposed perpendicular to one another. However, in other embodiments, the features 12 can be arranged non-perpendicularly relative to one another.

In FIGS. 7A-7B, the blocks 18 can have a first width t₁ that is larger than a second width t₂ of a gap G disposed between adjacent blocks 18. For example, in some embodiments, the first width t₁ can be in a range of 0.2 microns to 50 microns. The second width t₂ can be in a range of 0.1 microns to 25 microns. As shown in FIG. 7B, spacing the blocks 18 in such a manner can beneficially enable large regions of overlap between the conductive features 12 along the conductive bond 35, and result in multiple adjacent metal bond lines, which can be beneficial for sealing the bonded structure 1 from gases.

Although the lattice shown in FIGS. 7A-7B comprises a grid of intersecting conductive lines, in other embodiments, the lattice can comprise curved, periodic, or irregular shapes. For example, in some embodiments, the lattice can comprise a honeycomb structure of interconnected polygons. In some embodiments, the lattice can comprise a plurality of triangles, a herringbone pattern, or any other suitable lattice of repeating shapes.

FIG. 7C is a schematic plan view of the bonded interface structure 10 of FIG. 7B, with a plurality of electrical interconnects 20 disposed within the inner regions 114 a of the non-conductive interface features 14. As explained above in connection with FIG. 2B, it can be advantageous to incorporate additional conductive electrical interconnects 20 into the interface structure 10. Doing so enables the bonded structure 1 to provide a gas seal and electrical communication for a large number of signal, power and/or ground lines between the semiconductor elements 3, 2. In the embodiment of FIG. 7C, for example, the conductive interface features 12 and the non-conductive interface features 14 can provide a mechanical connection between the semiconductor elements 3, 2 that acts as an effective barrier to gases entering the structure. The conductive features 12 can comprise elongate features with a length greater than a width. The electrical interconnects 20 can be disposed within the inner regions 114 a and can be electrically isolated from the conductive features 12. The interconnects can extend vertically from the first semiconductor element 3 to the second semiconductor element 2 through the non-conductive features 14 to provide electrical communication between the semiconductor elements 3, 2. It will be understood that the effectively annular patter, e.g., a completely or mostly annular pattern, created by overlap and bonding of the two conductive features 12 can also serve as additional or sole electrical connection between the two semiconductor elements 3, 2.

Thus, in the embodiments of FIGS. 4B-7C, the first semiconductor element 3 can comprise a first pattern of repeating shapes formed from conductive lines on an exterior surface of the first semiconductor element 3. The first pattern can comprise a first conductive interface feature 12 spaced apart by a first spacing from a second conductive interface feature 12, with a first non-conductive interface feature 14 being disposed between the first and second conductive interface features 12. The first conductive interface feature 12 can have a first width that is greater than the first spacing. The second semiconductor element 2 can have a second pattern of repeating shapes formed from conductive lines on an exterior surface of the second semiconductor element 2. The second pattern can comprise a third conductive interface feature 12 spaced apart by a second spacing from a fourth conductive interface feature 12, with a second non-conductive interface feature 14 being disposed between the third and fourth conductive interface features 12. The third conductive interface feature 12 can have a second width that is greater than the second spacing. The first and second conductive interface features 12 can be bonded to the third and fourth conductive interface features 12 to define an interface structure 10. Even though the first and second patterns may be laterally offset relative to one another, the bonded first and second patterns can nevertheless delimit a continuous conductive bond region 35 along the interface structure 10.

FIG. 8 is a schematic diagram of an electronic system 80 incorporating one or more bonded structures 1, according to various embodiments. The system 80 can comprise any suitable type of electronic device, such as a mobile electronic device (e.g., a smartphone, a tablet computing device, a laptop computer, etc.), a desktop computer, an automobile or components thereof, a stereo system, a medical device, a camera, or any other suitable type of system. In some embodiments, the electronic system 80 can comprise a microprocessor, a graphics processor, an electronic recording device, or digital memory. The system 80 can include one or more device packages 82 which are mechanically and electrically connected to the system 80, e.g., by way of one or more motherboards. Each package 82 can comprise one or more bonded structures 1. The system 80 shown in FIG. 8 can comprise any of the bonded structures 1 and associated interface structure 10 shown and described herein.

In one embodiment, a bonded structure comprising is disclosed. The bonded structure can include a first element having a first interface feature, and a second element having a second interface feature. The bonded structure can include an integrated device coupled to or formed with the first element or the second element. The first interface feature can be directly bonded to the second conductive interface feature to define an interface structure. The interface structure can be disposed around the integrated device to define an effectively closed profile to connect the first and second elements. The effectively closed profile can substantially seal an interior region of the bonded structure from gases diffusing into the interior region from the outside environs.

In another embodiment, a bonded structure comprises a first element and a second element. The bonded structure can include an integrated device coupled to or formed within the first element or the second element. An interface structure can be disposed between the first element and the second element. The interface structure can comprise a first conductive interface feature extending in a direction from the first element to the second element, a second conductive interface feature extending in a direction from the first element to the second element, and a solid state non-conductive interface feature disposed laterally between the first and second conductive interface features. The interface structure can be disposed about the integrated device to define an effectively closed profile to connect the first element and the second element.

In another embodiment, a bonded structure comprises a first element and a second element. An integrated device can be coupled to or formed with the first element or the second element. An interface structure can be disposed between the first element and the second element, the interface structure extending in a direction from the first element to the second element. The interface structure can include a first elongate conductive interface feature extending in a direction from the first element to the second element and a second elongate conductive interface feature extending in a direction from the first element to the second element. The first and second elongate conductive interface features can be spaced apart by an intervening non-conductive interface feature extending in a direction from the first element to the second element. Each of the first and second elongate conductive interface features can have a length greater than a width. An electrical interconnect can be in electrical communication with the integrated device, the electrical interconnect extending from the first element to the second element. The electrical interconnect can extend through the intervening non-conductive interface feature between the first and second conductive interface features.

In another embodiment, a bonded structure comprises a first element having a first pattern of repeating shapes formed from conductive lines on an exterior surface of the first element. The first pattern can comprise a first conductive interface feature spaced apart by a first spacing from a second conductive interface feature, a first non-conductive interface feature being disposed between the first and second conductive interface features. The first conductive interface feature can have a first width that is greater than the first spacing. The bonded structure can comprise a second element having a second pattern of repeating shapes formed from conductive lines on an exterior surface of the second element. The second pattern can comprise a third conductive interface feature spaced apart by a second spacing from a fourth conductive interface feature. A second non-conductive interface feature can be disposed between the third and fourth conductive interface features, the third conductive interface feature having a second width that is greater than the second spacing. The first and second conductive interface features can be bonded to the third and fourth conductive interface features to define an interface structure. The first and second patterns can be laterally offset relative to one another but delimiting a continuous conductive bond region along the interface structure.

In another embodiment, a bonded structure is disclosed. The bonded structure can include a first element and a second element. An integrated device can be coupled to or formed with the first element or the second element. An interface structure can be disposed between the first element and the second element. The interface structure can comprise a first conductive interface feature laterally enclosing the integrated device. The conductive interface feature can continuously extend between the first and second elements to form at least one of an electrical, mechanical, or thermal connection between the two elements. A non-conductive interface feature can continuously extend between the first and second elements.

In another embodiment, a bonded structure can include a first element having a first interface feature and a second element having a second interface feature. The first interface feature can be bonded to the second interface feature to define an interface structure. A conductive trace can be disposed in or on the second element. A bond pad can be provided at an upper surface of the first element and in electrical communication with the conductive trace. An integrated device can be coupled to or formed with the first element or the second element.

In another embodiment, a bonded structure can comprise a first element having a first interface feature and a second element having a second interface feature. The first interface feature can be directly bonded to the second interface feature without an intervening adhesive to define an interface structure. A bond pad can be disposed at an upper surface of the first element. An integrated device can be coupled to or formed with the first element or the second element. An electrical interconnect can extend from the bond pad through the first element to electrically connect to the integrated device.

In another embodiment, a method of forming a bonded structure is disclosed. The method can comprise providing a first element having a first interface feature and a second element having a second interface feature. A conductive trace can be disposed in or on the second element. The method can comprise bonding the first interface feature and the second interface feature. A bond pad can be disposed at an upper surface of the first element and in electrical communication with the conductive trace. An integrated device can be coupled to or formed with the first element or the second element.

For purposes of summarizing the disclosed embodiments and the advantages achieved over the prior art, certain objects and advantages have been described herein. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosed implementations may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught or suggested herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

All of these embodiments are intended to be within the scope of this disclosure. These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of the embodiments having reference to the attached figures, the claims not being limited to any particular embodiment(s) disclosed. Although this certain embodiments and examples have been disclosed herein, it will be understood by those skilled in the art that the disclosed implementations extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while several variations have been shown and described in detail, other modifications will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the disclosed implementations. Thus, it is intended that the scope of the subject matter herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow. 

What is claimed is:
 1. A bonded structure comprising: a first element having a first interface feature; a second element having a second interface feature, the first interface feature bonded to the second interface feature to define an interface structure; a conductive trace disposed in or on the second element; a bond pad at an upper surface of the first element and in electrical communication with the conductive trace; and an integrated device coupled to or formed with the first element or the second element.
 2. The bonded structure of claim 1, wherein the first and second interface features are directly bonded to one another without an intervening adhesive.
 3. The bonded structure of claim 1, further comprising a cavity between the first and second elements.
 4. The bonded structure of claim 3, wherein the integrated device is disposed in the cavity.
 5. The bonded structure of claim 1, wherein no cavity is disposed in the bonded structure.
 6. The bonded structure of claim 1, wherein the interface structure is disposed around the integrated device to define an effectively closed profile to connect the first and second elements, the effectively closed profile substantially sealing an interior region of the bonded structure from gases diffusing into the interior region from the outside environs.
 7. The bonded structure of claim 1, further comprising an electrical interconnect extending from the conductive trace through the interface structure to connect to the bond pad.
 8. The bonded structure of claim 7, wherein the electrical interconnect extends through the first element.
 9. The bonded structure of claim 7, wherein the electrical interconnect extends through at least a portion of the second element.
 10. The bonded structure of claim 1, wherein one or both of the first and second interface features comprises a conductive interface feature.
 11. The bonded structure of claim 1, further comprising a plurality of bond pads disposed at the upper surface of the first element.
 12. The bonded structure of claim 1, wherein the integrated device is electrically connected to the conductive trace.
 13. The bonded structure of claim 1, wherein the bond pad is recessed relative to an uppermost surface of the bonded structure.
 14. The bonded structure of claim 1, wherein a lateral area of the second element is larger than a lateral area of the first element.
 15. A bonded structure comprising: a first element having a first interface feature; a second element having a second interface feature, the first interface feature directly bonded to the second interface feature without an intervening adhesive to define an interface structure; a bond pad at an upper surface of the first element; an integrated device coupled to or formed with the first element or the second element; and an electrical interconnect extending from the bond pad through the first element to electrically connect to the integrated device.
 16. The bonded structure of claim 15, wherein the electrical interconnect extends through the interface structure.
 17. The bonded structure of claim 16, wherein the electrical interconnect extends through a portion of the second element.
 18. The bonded structure of claim 15, further comprising a conductive trace in or on the second element, the conductive trace providing electrical communication between the integrated device and the electrical interconnect.
 19. The bonded structure of claim 15, further comprising a cavity between the first and second elements.
 20. The bonded structure of claim 15, wherein the interface structure is disposed around the integrated device to define an effectively closed profile to connect the first and second elements, the effectively closed profile substantially sealing an interior region of the bonded structure from gases diffusing into the interior region from the outside environs.
 21. A method of forming a bonded structure, the method comprising: providing a first element having a first interface feature and a second element having a second interface feature, a conductive trace being disposed in or on the second element; bonding the first interface feature and the second interface feature, wherein a bond pad is disposed at an upper surface of the first element and in electrical communication with the conductive trace, and wherein an integrated device is coupled to or formed with the first element or the second element.
 22. The method of claim 21, further comprising providing an electrical interconnect extending from the bond pad through the first element to electrically connect to the conductive trace.
 23. The method of claim 22, further comprising providing the electrical interconnect before the bonding.
 24. The method of claim 22, further comprising providing the electrical interconnect after the bonding.
 25. The method of claim 21, wherein bonding the first interface feature and the second interface feature comprises directly bonding the first interface feature and the second interface feature without an intervening adhesive. 